Narrow band photometry of Comet Halley in the emission bands and the continuum

Abstract

IHW filter photometry of Comet Halley was carried out on seven nights during pre-perihelion period and on six nights during post-perihelion period, using the 40-cm telescope at the Vainu Bappu Observatory, Kavalur, as a part of the Indian Halley Observation Program. The pre-perihelion observations show large amplitude fluctuations in the emission fluxes, superimposed on the general trend of their slow increase with the decreasing R(h). The respective abundances of the CN, C3, CO(+), C2 and H2O(+) molecules contained in a cylinder of diameter 86 arcsec in the line of sight through the comet have also been estimated. Their individual emission strengths are very low due perhaps to the comet's several approaches to the sun.